From 2afbdba1c537a7c0872271a119bb35d8724e7c12 Mon Sep 17 00:00:00 2001
From: Travis Turner <travis@pilosa.com>
Date: Wed, 13 Dec 2017 08:22:58 -0600
Subject: [PATCH] add lock protection around gossip.memberlist and
 holder.indexes

---
 gossip/gossip.go | 11 +++++++++++
 holder.go        |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/gossip/gossip.go b/gossip/gossip.go
index 9d5845315..35f0056c8 100644
--- a/gossip/gossip.go
+++ b/gossip/gossip.go
@@ -20,6 +20,7 @@ import (
 	"log"
 	"os"
 	"strings"
+	"sync"
 	"time"
 
 	"golang.org/x/sync/errgroup"
@@ -37,6 +38,7 @@ var _ memberlist.Delegate = &GossipMemberSet{}
 
 // GossipMemberSet represents a gossip implementation of MemberSet using memberlist.
 type GossipMemberSet struct {
+	mu         sync.RWMutex
 	memberlist *memberlist.Memberlist
 	handler    pilosa.BroadcastHandler
 
@@ -51,6 +53,9 @@ type GossipMemberSet struct {
 
 // Nodes implements the MemberSet interface and returns a list of nodes in the cluster.
 func (g *GossipMemberSet) Nodes() []*pilosa.Node {
+	g.mu.RLock()
+	defer g.mu.RUnlock()
+
 	a := make([]*pilosa.Node, 0, g.memberlist.NumMembers())
 	for _, n := range g.memberlist.Members() {
 		uri, _ := pilosa.NewURIFromAddress(n.Name)
@@ -78,13 +83,17 @@ func (g *GossipMemberSet) Open() error {
 	}
 
 	err := error(nil)
+	g.mu.Lock()
 	g.memberlist, err = memberlist.Create(g.config.memberlistConfig)
+	g.mu.Unlock()
 	if err != nil {
 		return err
 	}
 
 	g.broadcasts = &memberlist.TransmitLimitedQueue{
 		NumNodes: func() int {
+			g.mu.RLock()
+			defer g.mu.RUnlock()
 			return g.memberlist.NumMembers()
 		},
 		RetransmitMult: 3,
@@ -98,7 +107,9 @@ func (g *GossipMemberSet) Open() error {
 	// attach to gossip seed node
 	nodes := []*pilosa.Node{&pilosa.Node{URI: *uri}} //TODO: support a list of seeds
 
+	g.mu.RLock()
 	err = g.joinWithRetry(pilosa.NodeSet(pilosa.Nodes(nodes).URIs()).ToHostPortStrings())
+	g.mu.RUnlock()
 	if err != nil {
 		return err
 	}
diff --git a/holder.go b/holder.go
index 4c3d476d2..9a1d793d5 100644
--- a/holder.go
+++ b/holder.go
@@ -156,7 +156,9 @@ func (h *Holder) Open() error {
 			}
 			return fmt.Errorf("open index: name=%s, err=%s", index.Name(), err)
 		}
+		h.mu.Lock()
 		h.indexes[index.Name()] = index
+		h.mu.Unlock()
 	}
 	h.logger().Printf("open holder: complete")
 
@@ -190,6 +192,8 @@ func (h *Holder) Close() error {
 // This is used to determine if the rebalancing of data is necessary
 // when a node joins the cluster.
 func (h *Holder) HasData() bool {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
 	return h.hasData || len(h.indexes) > 0
 }